References of "Garraux, Gaëtan"
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See detailEffects of 10Hz and 20Hz transcranial alternating current stimulation on automatic motor control
Cappon, Davide; D'Ostilio, Kevin ULg; Garraux, Gaëtan ULg et al

in Brain Stimulation (in press)

Background: Automatic motor inhibition is an important and adaptive process through which an activated motor plan is suppressed if the movement is not intended to be executed. Neuronal networks are ... [more ▼]

Background: Automatic motor inhibition is an important and adaptive process through which an activated motor plan is suppressed if the movement is not intended to be executed. Neuronal networks are characterized by oscillatory activity. In the brain, a large variety of rhythms have been described that differ in their frequency, origin and reactivity to changes in task demands. Recent studies have demonstrated that active cortical networks are susceptible to weak sinusoidal perturbations of exogenous electric fields. Objective/Hypothesis: The aim of this study was to investigate the frequency-specific effect of transcranial alternate current stimulation (tACS) over the automatic control of movement in healthy volunteers. We hypothesized that applying two different tACS frequencies during a visuo-motor task would result in different behavioural effects and in diverse modulation of cortical excitability. Methods: In this study we used tACS to interact non-invasively with the ongoing task-related oscillatory activity. Stimulation was delivered at alpha (10 Hz) and beta (20 Hz) frequency over the supplementary motor area and the primary motor cortex (SMA-M1) connections, which are part of the BG-cortical motor loop, during the execution of the subliminal masked prime task. We measured the effects on task performance and on motor cortex corticospinal excitability by means of motor evoked potentials (MEPs) evoked by transcranial magnetic stimulation (TMS). Results: Results indicate a specific effect of 10 and 20-Hz tACS on functional inhibition in the SMA-M1 circuit. Behaviorally there is an interference in task-related automatic inhibition: 10 Hz tACS reduced the automatic inhibition. In contrast 20 Hz tACS increased the automatic inhibition. At a neurophysiological level there is a modulation in excitability of M1: 20 Hz tACS reduced MEP amplitudes, whereas there was no change after 10 Hz tACS. Conclusion(s): The current study provides novel evidence that automatic mechanisms of motor behaviour can be modulated by imposing synchronized electrical oscillatory activity upon motor cortical regions. Our study has important implications for cognitive neuroscience studies suggesting that the use tACS might offer the possibility to demonstrate a causal link between endogenous brain oscillations, specific exogenous alternate current frequencies and specific cognitive processes. [less ▲]

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See detailThe network model of depression as a basis for new therapeutic strategies for treating major depressive disorder in Parkinson’s disease
D'Ostilio, Kevin ULg; Garraux, Gaëtan ULg

in Frontiers in Human Neuroscience (in press)

The high prevalence of major depressive disorder in people with Parkinson's disease, its negative impact on health-related quality of life and the low response rate to conventional pharmacological ... [more ▼]

The high prevalence of major depressive disorder in people with Parkinson's disease, its negative impact on health-related quality of life and the low response rate to conventional pharmacological therapies call to seek innovative treatments. Here, we review the new approaches for treating major depressive disorder in patients with Parkinson's disease within the framework of the network model of depression. According to this model, major depressive disorder reflects maladaptive neuronal plasticity. Non-invasive brain stimulation using high frequency repetitive transcranial magnetic stimulation over the prefrontal cortex has been proposed as a feasible and effective strategy with minimal risk. The neurobiological basis of its therapeutic effect may involve neuroplastic modifications in limbic and cognitive networks. However, the way this networks reorganize might be strongly influenced by the environment. To address this issue, we propose a combined strategy that includes non-invasive brain stimulation together with cognitive and behavioral interventions. [less ▲]

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See detailGait pattern of healthy old people for fast walking condition
GILLAIN, Sophie ULg; Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg et al

in Gerontechnology (2016, September)

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See detailGait pattern of healthy old people for fast walking condition
GILLAIN, Sophie ULg; Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg et al

in Gerontechnology (2016, September)

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See detailGait pattern of healthy old people for fast walking condition
GILLAIN, Sophie ULg; Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg et al

in Gerontechnology (2016, September)

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See detailGait pattern of healthy old people for fast walking condition
GILLAIN, Sophie ULg; Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg et al

in Gerontechnology (2016, September)

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See detailGait pattern of healthy old people for dual task walking condition
GILLAIN, Sophie ULg; Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg et al

in Gerontechnology (2016, September)

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See detailExtraction of temporal gait parameters using a reduced number of wearable accelerometers
Boutaayamou, Mohamed ULg; Denoël, Vincent ULg; Bruls, Olivier ULg et al

in Proceedings of the 9th International Conference on Bio-inspired Systems and Signal Processing (2016)

Wearable inertial systems often require many sensing units in order to reach an accurate extraction of temporal gait parameters. Reconciling easy and fast handling in daily clinical use and accurate ... [more ▼]

Wearable inertial systems often require many sensing units in order to reach an accurate extraction of temporal gait parameters. Reconciling easy and fast handling in daily clinical use and accurate extraction of a substantial number of relevant gait parameters is a challenge. This paper describes the implementation of a new accelerometer-based method that accurately and precisely detects gait events/parameters from acceleration signals measured from only two accelerometers attached on the heels of the subject’s usual shoes. The first step of the proposed method uses a gait segmentation based on the continuous wavelet transform (CWT) that provides only a rough estimation of motionless periods defining relevant local acceleration signals. The second step uses the CWT and a novel piecewise-linear fitting technique to accurately extract, from these local acceleration signals, gait events, each labelled as heel strike (HS), toe strike (TS), heel-off (HO), toe-off (TO), or heel clearance (HC). A stride-by-stride validation of these extracted gait events was carried out by comparing the results with reference data provided by a kinematic 3D analysis system (used as gold standard) and a video camera. The temporal accuracy ± precision of the gait events were for HS: 7.2 ms ± 22.1 ms, TS: 0.7 ms ± 19.0 ms, HO: ‒3.4 ms ± 27.4 ms, TO: 2.2 ms ± 15.7 ms, and HC: 3.2 ms ± 17.9 ms. In addition, the occurrence times of right/left stance, swing, and stride phases were estimated with a mean error of ‒6 ms ± 15 ms, ‒5 ms ± 17 ms, and ‒6 ms ± 17 ms, respectively. The accuracy and precision achieved by the extraction algorithm for healthy subjects, the simplification of the hardware (through the reduction of the number of accelerometer units required), and the validation results obtained, convince us that the proposed accelerometer-based system could be extended for assessing pathological gait (e.g., for patients with Parkinson’s disease). [less ▲]

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See detailIn vivo quantification of dopaminergic terminals loss in Parkinson’s Disease rat model: comparison between [18F]FMT and [18F]FDOPA.
Becker, Guillaume ULg; Bahri, Mohamed Ali ULg; Michel, Anne et al

Poster (2015, September 02)

Objectives: Rat models of Parkinson’s disease (PD), such as unilaterally lesioned rats with 6-hydroxydopamine (6-OHDA), are useful to evaluate novel antiparkinsonian therapies. MicroPET imaging, using L-3 ... [more ▼]

Objectives: Rat models of Parkinson’s disease (PD), such as unilaterally lesioned rats with 6-hydroxydopamine (6-OHDA), are useful to evaluate novel antiparkinsonian therapies. MicroPET imaging, using L-3,4-dihydroxy-6-[18F]-fluoro-phenylalanine ([18F]FDOPA) allows longitudinal evaluations of DA terminals loss. However, chemical structure of [18F]FDOPA leads to suboptimal PET imaging. 18F-fluoro-m-tyrosine ([18F]FMT) is an effective PET tracer to evaluate DA terminals integrity and L-aromatic amino acid decarboxylase (AAAD) metabolic pathway. So far, there are no available quantitative PET studies comparing the two methods in hemiparkinsonian rats. In this study, we compare imaging data provided by [18F]FMT PET and [18F]FDOPA PET in 6-OHDA-lesioned rats. Methods: 10 µg of 6-OHDA were injected into the right medial forebrain bundle (MFB) of male Sprague-Dawley rats (n=8). As control, sham-treated rats (n=8) were injected with vehicle only but otherwise treated identically. Striatal DA presynaptic activity was assessed by dynamic PET with both [18F]FMT and [18F]FDOPA. Structural T2-weighted brain images were acquired on a 9.4T MRI and were used for co-registration. After normalization on a MRI template, kinetic analysis was performed by “Patlak Reference” model, using PMOD software. Six days after the last PET scan, rats were sacrificed, and striatum were rapidly removed for striatal DA and metabolites quantification. Results: Striatal accumulation was observed for both tracers. However, while the administration of [18F]FDOPA required two peripheral inhibitors (benserazide and entacapone), only benserazide is needed with [18F]FMT. As consequence of the 6-OHDA-lesion, significant decrease of both [18F]FMT and [18F]DOPA accumulation was recorded in the striatum ipsilateral to the lesion. Lesioned rats had dramatically reduced uptake constant Ki in the ipsilateral striatum compared to the contralateral striatum (p<0.001 for [18F]FMT and p<0.05 for [18F]DOPA) and to the ipsilateral striatum of sham-treated rats (p<0.001 for both tracers). The DA content in the ipsilateral striatum was significantly lower (p<0.001) than in the contralateral striatum in the 6-OHDA-injected group, whereas such difference was not measured with the sham group. This indicate that [18F]FMT PET is as effective as [18F]DOPA PET to quantify loss of DA presynaptic function in unilaterally 6-OHDA lesioned rats. Conclusions: Our results are in agreement with data reporting correlation between these two tracers in a Non-human primate model of PD. The sensitivity of the data quantification obtained in this study, confirms the interest to pursue longitudinal investigations with [18F]FMT to monitor dopaminergic dysfunction in a more progressive preclinical model of PD. [less ▲]

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See detailQuestion Intégrative - Médecine - Module Système Nerveux
Pasquet, Coralie ULg; Van de Poël, Jean-François ULg; Schaffer, Patrick ULg et al

Poster (2015, May 18)

Au cours du premier quadrimestre de l’année académique 2014 - 2015, une nouvelle activité a été proposée aux 270 étudiants inscrits en 3ième année du grade de Bachelier en Médecine à l’Université de Liège ... [more ▼]

Au cours du premier quadrimestre de l’année académique 2014 - 2015, une nouvelle activité a été proposée aux 270 étudiants inscrits en 3ième année du grade de Bachelier en Médecine à l’Université de Liège. Cette activité a été réalisée dans le cadre du « Module Système Nerveux ». [less ▲]

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See detail[18F]FMT: a reliable PET tracer for in vivo evaluation of dopaminergic dysfunction in Parkinson’s Disease rat model.
Seret, Alain ULg; Becker, Guillaume ULg; Bahri, Mohamed Ali ULg et al

Poster (2015, May 09)

Background: Rat models of Parkinson’s disease (PD), such as lesioned rats with 6-hydroxydopamine (6-OHDA), are useful for studying dopamine (DA)-related functions. 6-[18F]fluoro-m-tyrosine (6-[18F]FMT) is ... [more ▼]

Background: Rat models of Parkinson’s disease (PD), such as lesioned rats with 6-hydroxydopamine (6-OHDA), are useful for studying dopamine (DA)-related functions. 6-[18F]fluoro-m-tyrosine (6-[18F]FMT) is an effective PET tracer to evaluate of DA terminals integrity and L-aromatic amino acid decarboxylase (AAAD) metabolic pathway. However, there are currently no available quantitative PET studies using [18F]FMT in 6-OHDA lesioned rats. In this context, we investigated the feasibility of in vivo PET study using [18F]FMT on 6-OHDA PD’s model. Methods: 10 µg of 6-OHDA were injected into the right medial forebrain bundle (MFB) of male Sprague-Dawley rats (n=8). As control, sham-treated rats (n=8) were injected with vehicle only but otherwise treated identically. Striatal DA presynaptic activity was assessed by dynamic [18F]FMT PET, 30 min after benserazide pretreatment. Structural T2-weighted brain images were acquired on a 9.4T MRI and were used for co-registration. After normalization on a MRI template, kinetic analysis was performed by “Patlak Reference” model, using PMOD software. Results: Striatal accumulation of [18F]FMT was observed in rats pretreated with benserazide, a peripheral AAAD inhibitor. As consequence of the 6-OHDA-lesion, significant decrease of [18F]FMT accumulation was recorded in the striatum ipsilateral to the lesion. Lesioned rats had dramatically reduced uptake constant Ki in the ipsilateral striatum compared to the contralateral striatum (p<0.001) and to the ipsilateral striatum of sham-treated rats (p<0.005). The Ki ratio (Ipsi./Contra.) was equivalent to 94% in the sham group and dropped to 41% in the lesioned group. Conclusions: [18F]FMT PET enables us to quantify loss of DA presynaptic function in unilaterally 6-OHDA lesioned rats. These results encourage us to pursue further investigations in a longitudinal way and to monitor the progression of the dopaminergic dysfunction in more moderate and gradual preclinical PD models. [less ▲]

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See detail18F-FMT: a reliable PET tracer for in vivo evaluation of dopaminergic dysfunction in Parkinson’s Disease rat model.
Becker, Guillaume ULg; Bahri, Mohamed Ali ULg; Michel, Anne et al

Poster (2015, March 18)

Objectives: Rat models of Parkinson’s disease (PD), such as lesioned rats with 6-hydroxydopamine (6-OHDA), are useful for studying dopamine (DA)-related functions. 6-18F-fluoro-m-tyrosine (6-18F-FMT) is ... [more ▼]

Objectives: Rat models of Parkinson’s disease (PD), such as lesioned rats with 6-hydroxydopamine (6-OHDA), are useful for studying dopamine (DA)-related functions. 6-18F-fluoro-m-tyrosine (6-18F-FMT) is an effective PET tracer to evaluate of DA terminals integrity and L-aromatic amino acid decarboxylase (AAAD) metabolic pathway. However, there are currently no available quantitative PET studies using 18F-FMT in 6-OHDA lesioned rats. In this context, we investigated the feasibility of in vivo PET study using 18F-FMT on 6-OHDA PD’s model. Methods: 10 µg of 6-OHDA were injected into the right medial forebrain bundle (MFB) of male Sprague-Dawley rats (n=8). As control, sham-treated rats (n=8) were injected with vehicle only but otherwise treated identically. Striatal DA presynaptic activity was assessed by dynamic 18F-FMT-PET. Structural T2-weighted brain images were acquired on a 9.4T MRI and were used for co-registration. After normalization on a MRI template, kinetic analysis was performed by “Patlak Reference” model, using PMOD software. Results: Striatal accumulation of 18F-FMT was observed in rats pretreated with benserazide, a peripheral AAAD inhibitor. As consequence of the 6-OHDA-lesion, significant decrease of 18F-FMT accumulation was recorded in the striatum ipsilateral to the lesion. Lesioned rats had dramatically reduced uptake constant Ki in the ipsilateral striatum compared to the contralateral striatum (p<0.001) and to the ipsilateral striatum of sham-treated rats (p<0.005). The Ki ratio (Ipsi./Contra.) was equivalent to 94% in the sham group and dropped to 41% in the lesioned group. Conclusions: 18F-FMT PET enables us to quantify loss of DA presynaptic function in unilaterally 6-OHDA lesioned rats. These results encourage us to pursue further investigations in a longitudinal way and to monitor the progression of the dopaminergic dysfunction in more moderate and gradual preclinical PD models. [less ▲]

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See detailGait quantification through accelerometers and clinical tests: application to pathological gait
DEMONCEAU, Marie ULg; Boutaayamou, Mohamed ULg; Maquet, Didier ULg et al

Conference (2015, January 30)

Gait gives essential information to physiotherapists in the screening and follow-up of their patients suffering from orthopaedic, geriatric or neurologic diseases. Most of time, clinical practitioners ... [more ▼]

Gait gives essential information to physiotherapists in the screening and follow-up of their patients suffering from orthopaedic, geriatric or neurologic diseases. Most of time, clinical practitioners rely on visual observation of their patients during specific clinical tests that can highlight gait abnormalities (e,g., the Tinetti assessment tool, the timed up and go test, the 6 minutes walking test), but these tests provide little quantified information about gait. These rough methods are also limited by inter-rater subjectivity and lack of acuteness in the detection of subtle impairments. On the other hand, instrumented gait analyses offer a sharper investigation with the ability to record and quantify gait events that cannot be caught at simple visual observation. Unfortunately, cutting edge technologies often pay the price of a limited number of strides extracted, the need of a strictly controlled laboratory environment, development and maintenance by a specialized staff. For these reasons, instrumented gait analysis may stand beyond the financial and technical reach of many rehabilitative centres and private practitioners. Accelerometer technologies have considerably developed with the progress of wireless technologies. These lightweight and low-cost sensors allow quantified gait analyses that are not restricted to a laboratory environment but can also be used in medical offices and in combination with common clinical gait tests. This presentation relates the experiences of our departments with accelerometer systems and clinical testing in gait analysis of patients suffering from Parkinson’s disease. The aim of this intervention is to cross ideas and knowledge of clinical practitioners and engineers in the development a new gait analysis tool that could integrate routine evaluation of patients suffering from Parkinson’s disease and other conditions characterized by gait impairments. [less ▲]

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